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/*
* Copyright (C) by Argonne National Laboratory
* See COPYRIGHT in top-level directory
*/
/* A very simple program that performs only a send and a receive. This
program can be use with logging enabled (configure with
--enable-g=dbg,log) and run with -mpich-dbg-class=routine to get
a trace of the execution of the functions in MPICH */
#include <stdio.h>
#include "mpi.h"
#define SENDER_RANK 0
#define RECEIVER_RANK 1
int main(int argc, char *argv[])
{
int rank, size, val;
MPI_Status status;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &size);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
if (size < 2) {
fprintf(stderr, "This program requires at least 2 processes\n");
MPI_Abort(MPI_COMM_WORLD, 1);
}
if (rank == SENDER_RANK) {
MPI_Send(&rank, 1, MPI_INT, RECEIVER_RANK, 0, MPI_COMM_WORLD);
} else if (rank == RECEIVER_RANK) {
/* This may or may not post the receive before the send arrives */
MPI_Recv(&val, 1, MPI_INT, SENDER_RANK, 0, MPI_COMM_WORLD, &status);
}
/* Perform a second send/receive to allow the first pair to handle
* any connection logic */
#if 1
if (rank == SENDER_RANK) {
MPI_Send(&rank, 1, MPI_INT, RECEIVER_RANK, 0, MPI_COMM_WORLD);
} else if (rank == RECEIVER_RANK) {
/* This may or may not post the receive before the send arrives */
MPI_Recv(&val, 1, MPI_INT, SENDER_RANK, 0, MPI_COMM_WORLD, &status);
}
#endif
MPI_Finalize();
return 0;
}
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